This year there has been a huge buzz in the world of modern web development with edge functions, edge computing or more awkwardly phrased as "running your code at the edge."
It's not some new punk band. It's the next phase in how we build fast, scalable applications and it isn't hype.
So, what are edge functions? Why should you care? And how do they fit into modern stacks?
First, What Is the Edge?
In the traditional model, when someone requests your app, it hits a centralized server, sometimes in Virginia, and sometimes in Germany, or California, or an enormous AWS data center half a world away in a different timezone.
And that's all okay. But you're in Tokyo and your server is in New York City - that's going to be a pretty big physical distance. And even if you're on fast internet, you've got latency to account for.
The edge is about running your code on servers that are as physically close to your users as possible. Instead of having one origin server - you're deploying to lots and lots of little servers around the world. The benefit? Reduced latency, faster response times, and happy users.
So... What Are Edge Functions?
Edge functions are like mini serverless functions that run at those edge locations. Think:
Middleware logic
Authentication checks
A/B testing
Personalization
Redirects, rewrites
Low-latency APIs
They’re small, fast, and often run in lightweight environments like V8 isolates, not full Node.js processes. This means they spin up quickly and run with minimal cold start.
Popular platforms supporting edge functions include:
Vercel Edge Functions
Cloudflare Workers
Netlify Edge Functions
Deno Deploy
Bun (experimental edge support)
Why Are They a Big Deal?
Let’s break down why edge functions are such a modern dev darling:
Speed Matters
The closer your logic runs to your user, the faster your app feels. We're talking milliseconds saved on every request. That adds up, especially for global apps.Dynamic Logic Without a Heavy Server
You can run logic like authentication or header manipulation without needing a full server. It’s like CDN rules, but on steroids.Scalability by Default
No need to think about traffic spikes or managing infrastructure. Edge functions scale globally and automatically, just like serverless.Plays Well With Modern Stacks
Edge functions fit naturally into JAMstack and headless architectures. They’re great when paired with static sites and APIs, letting you add just the right amount of dynamic behavior.
What Edge Functions Are Not Great At
Let’s be real: edge functions aren’t a silver bullet.
Cold starts still exist, though they’re faster than traditional serverless.
No file system: Most edge environments are sandboxed, no reading/writing to disk.
Limited runtime: Many edge providers don’t support full Node.js. That means no native modules or heavy server-side logic.
Memory & execution time caps: They’re built for small tasks, not running a whole backend.
In short, edge functions are great for lightweight, latency-sensitive tasks, not your whole monolithic app.
Should You Use Them?
If you’re building a modern web app, especially one with a global audience, edge functions are worth exploring. They're perfect for:
Running authentication logic at the edge before hitting your backend
Serving geo-personalized content
Speeding up routing decisions
Rate limiting
Feature flag evaluation
Start small. Try using one for middleware. See how it affects performance. The tooling has gotten really developer-friendly in the last couple years.
Edge functions are one of those “sounds cool, but do I need it?” tools. But once you start to see them in action, particularly in combination with static files or headless CMS's: they begin to feel like magic.
Let me know if you would want a follow-up post with hands-on examples (like building an auth layer at the edge or using Cloudflare Workers for caching tricks).
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